Generally, automatic transmission devices for automobiles, which include automatic transmissions and stepless transmissions for vehicles, include, as components that constitutes a gear shift mechanism or other components, torque transmission mechanisms such as various types of rotational axis and gears, and are configured such that the gear ratio is changed depending on the path through which the torque is transmitted through some of such torque transmission mechanisms. An oil pump is provided for generating hydraulic pressure for driving these mechanisms to change the gearshift ratio or for the purpose of lubrication.
The mechanism proposed in Patent Literature 1 can be given as a typical example of the mechanism for driving an oil pump that is applied to an automatic transmission device in which an oil pump as described above is arranged on an axis different from an input shaft.
In the oil pump drive mechanism disclosed in Patent Literature 1, a drive sprocket provided in the outer peripheral portion of a torque converter sleeve and a driven sprocket provided in the oil pump are linked with a chain, thereby driving the oil pump with the drive force of the engine. Since a torque converter cover expands due to an increase in the oil temperature or hydraulic pressure in the torque converter, the torque converter sleeve is required to be movable to some extent in the axis direction. Therefore, the outer periphery surface of the torque converter sleeve and the inner periphery surface of the drive sprocket are fitted to each other so as to be respectively movable in the axis direction, the drive sprocket is axially supported, and the drive force is transmitted while allowing the movement thereof in the axial direction.
Also in Patent Literature 2, an oil pump drive mechanism that can improve durability and prevent noise is proposed.
With the technique disclosed in Patent Literature 2, in an oil pump drive mechanism in which an oil pump is arranged in a position separated from the rotational axis of the torque converter in the radial direction thereof, and a first sprocket that rotates about the rotational axis and a second sprocket that drives the oil pump are linked with a chain, a first cylinder portion is formed that is on the outer periphery of the rotational axis of the torque converter, is driven integrally with the input side of the torque converter, and is fitted into the first sprocket, and a second cylinder portion as a fixed member is formed on the inner periphery of the first cylinder portion, and a first bearing that supports the first cylinder portion to the second cylinder portion and a second bearing that supports the first sprocket to the second cylinder portion are provided.
Furthermore in Patent Literature 3, an oil pump drive mechanism for an automatic transmission is proposed that can reduce friction caused by the rotation of the sprocket, while restraining attachment backlash of the sprocket.
In the technique disclosed in Patent Literature 3, in the oil pump drive mechanism of automatic transmission that drives an oil pump arranged in a position separated from the rotation center axis of the torque converter in the radial direction thereof, the first sprocket is supported to the torque converter housing so as to be freely rotatable, by a first bearing loaded in the radial direction and a second bearing loaded in the thrust direction, a sealing is provided for achieving liquid-tightness between the first sprocket and the cover, and thrust force toward the second bearing is applied to the first sprocket with the use of the hydraulic pressure supplied to the oil chamber formed between the first sprocket and the cover.